Several publications and patent documents are cited throughout the specification in order to describe the state of the art to which this invention pertains. Each of these citations is incorporated herein by reference as though set forth in full.
Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive squamous cell cancers compared to those originating at other sites, such as skin, head/neck, lung and anogenital tract. The reasons underlying these differences are somewhat surprising in that there is commonality in the type and frequency of pivotal genetic alterations and environmental exposures. In this context, the prognosis for patients with ESCC remains poor, due to the high rate of local and distant metastases at time of diagnosis (Enzinger and Mayer (2003) N. Engl. J. Med. 349:2241-52) Common genetic alterations identified in ESCC include epidermal growth factor receptor (EGFR) (up to 70%) and cyclin D1 oncogene overexpression (up to 60-70%), inactivation of the p53 (50-60%) and p16INK4a (40-50%) tumor suppressor genes, and hTERT activation (Mandard et al. (2000) Mutat. Res. 462: 335-342; Metzger et al. (2004) Onkologie 27: 200-206); Sunpaweravong et al. (2005) J. Cancer Res. Clin. Oncol. 131:111-119). Cyclin D1 and EGFR overexpression appear to be associated with early events in tumor initiation, in particular with preneoplastic (squamous dysplasia) and early neoplastic stages, whereas p53 and p16 inactivation are associated with tumor progression in advanced neoplastic stages (Mandard et al. (2000) supra; Okano et al. (2003) Meth. Mol. Biol. 222:131-145). While these are the canonical genetic alterations that delineate ESCC initiation and progression, genomic approaches have added to the library of other genes and pathways that are important, although not as compelling in terms of high frequency.
Genetic alterations in epithelial tumors, such as squamous cell cancers, help to drive tumor cell migration and invasion into the extracellular matrix. The mesenchymal stroma (or connective tissue) is essential for the maintenance of the epithelium. Genetically altered epithelial cells modify the stromal compartment so as to establish a permissive and supportive environment for cancer cell invasion (Unger and Weaver (2003) Meth. Mol. Biol. 223:315-347). The fibroblasts are one of several cell types involved in the stromal compartment mediated regulation of epithelial cancer (Beacham and Cukierman (2005) Semin. Cancer Biol. 15:329-341). The fibroblastic population is very heterogeneous and it varies from tissue to tissue and from site to site. It is however accepted to define fibroblasts as the cells responsible for producing, maintaining and modifying the extracellular matrices of connective tissue. These cells are normally spindled or stellate in shape and are responsible for maintaining homeostatic equilibrium in connective (or mesenchymal) compartments. Fibroblasts are characterized as being vimentin positive, E-cadherin negative and spindle-shaped in 2D cultures as well as 3D matrices (Amatangelo et al. (2005) Am. J. Pathol. 167:475-488).
The fibroblasts in the cancer stroma are activated myofibroblasts or cancer associated fibroblasts (Beacham and Cukierman (2005), supra. In some cases, the trigger for neoplastic progression may come from signals within the stromal microenvironment (Radisky et al. (2001) Semin. Cancer Biol. 11:87-95; Maffini et al. (2004) J. Cell Sci. 117:1495-1502). It is increasingly apparent that mesenchymal stromal fibroblasts modulate tumor cell migration and invasion through autocrine and paracrine mechanisms involving, in part, secreted growth factors and cytokines. In addition, both epithelial cells and stromal fibroblasts produce enzymes that degrade the epithelial basement membrane, as well as the mesenchymal ECM (Liotta et al. (1991) Nature 284:67-68), such as matrix metalloproteinases (MMPs). Tumor cell invasion into the ECM with subsequent metastasis to distant organs via hematogenous and lymphatic dissemination are critical steps in tumor viability and progression (Gupta and Massague (2006) Cell 127:679-695).